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Proceedings Paper

Estimating Cn2 Over Snow And Sea Ice From Meteorological Quantities
Author(s): Edgar L Andreas
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Paper Abstract

Because turbulent fluctuations in the atmospheric refractive index (n) at wavelength x are related to turbulent fluctuations in the temperature (t) and humidity (q) by n = A(x,P,T,9)t + B(x,P,T,Q)q, it is possible to estimate the refractive index structure parameter C in the atmospheric surface layer from meteorological quantities. I describe two such estimation procedures, one based on the velocity, temperature, and humidity scales u*' t*, and q*, and a second based on the routine meteorological quantities U,, T -Th, and %-Q,. Subscript h here denotes the wind speed (U,), temperature (TO, and humidity (Qh) at rVference height h; subscript s indicates the sUrface value. I tabulate the coefficients A and B as functions of λ, the atmospheric pressure (I)), and the ambient temperature (T) and humidity (Q) in four wavelength regions--visible (including near-infrared), an infrared window, near-millimeter, and radio. A sensitivity analysis of the two estimation procedures demonstrates that the accuracy of the Cn2 estimate is a strong function of the Bowen ratio (Bo), the ratio of sensible to latent heat flux at the surface. At two Bo values within the interval [-10,10], one dependent on λ and the other on enyironmental conditions, the uncertainty in the Cn2 estimate becomes infinite. I focus on C values over snow and sea ice, and my examples are for these surfaces, but the estimation procedures presented can be applied to any geophysical surface that is horizontally homogeneous.

Paper Details

Date Published: 10 August 1988
PDF: 10 pages
Proc. SPIE 0926, Optical, Infrared, Millimeter Wave Propagation Engineering, (10 August 1988); doi: 10.1117/12.945784
Show Author Affiliations
Edgar L Andreas, U.S. Army Cold Regions Research and Engineering Laboratory (United States)


Published in SPIE Proceedings Vol. 0926:
Optical, Infrared, Millimeter Wave Propagation Engineering
Norman S. Kopeika; Walter B. Miller, Editor(s)

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